Habitat associations of imperilled fishes after conservation intervention in the Cape Fold Ecoregion, South Africa

Abstract

The aim of this study was to examine the habitat associations of a native cyprinid community of the recovering Rondegat River in the Cape Fold Ecoregion of South Africa as part of a long-term native fish abundance monitoring project. Relative abundance data were extracted from underwater video camera footage across the longitudinal gradient of the river in three sampling instances. Using multivariate methods the authors assessed community composition with respect to habitat, its overlap with a protected area and species-specific abiotic predictors of relative abundance. Distance from the uppermost site in the river was the most significant predictor of species abundance, indicating spatial segregation and varying overlap between species. The protected status of sites in the upper reaches, vegetated substrates and the size of individual sites were the most impactful on the relative abundance of the endangered fiery redfin Pseudobarbus phlegethon. The results of this study indicate that underwater video monitoring is an effective and low-cost approach that can inform conservation recommendations. Reducing agricultural runoff and sedimentation in the lower reaches may be useful further interventions to maintain key habitats of submerged vegetation.

Review of fish community, stressors and conservation in the Rondegat River (South Africa)

“…Pseudobarbus phlegethon feeds on detritus attached to the rocky substrate and aquatic invertebrates (Skelton, 1996;Whitehead, Weyl & Bills, 2007;Garrow & Marr, 2012). Habitat preferences for this species tend to be slow-flowing pool environments with complex structure (Gore, King & Hamman, 1991;Broom et al, 2022). A preference for substrate foraging is suggested by this species' sub-terminal mouth orientation (Whitehead et al, 2007).…”

“…They are generally only found abundantly in the lower reaches as older, larger individuals persist in deeper oversummering pools (Paxton, 2008;Weyl et al, 2013;van der Walt et al, 2016). Labeobarbus seeberi is likely dependent on these pools for both over-summering refugia as well as important congregation areas for drift and substrate feeding downstream of riffles (Impson et al, 2008;Paxton, 2008;Broom et al, 2022). Labeobarbus seeberi is expected to have an omnivorous diet, with a fairly even representation of plant material and invertebrate prey (Paxton, 2008).…”

“…Isolated populations are particularly important for conservation in G. zebratus, as very finescale differentiation and speciation is commonly observed in this putative species complex (Wishart et al, 2006). The limited distribution and low number of known populations of P. phlegethon also warrant attention in the context of fire events affecting the Rondegat River (Broom et al, 2022).…”